package dao.impl;

import dao.UserDao;
import pojo.User;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class UserDaoImpl implements UserDao {
    @Override
    public List<User> findAll() {
        // jdbc 操作
        // 创建集合
        List<User> users = new ArrayList<>();
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        // 1、加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 2、获取连接 (url username password)
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "200522");
            // 3、写sql
            String sql = "select * from user";
            // 4、预编译sql
            preparedStatement = connection.prepareStatement(sql);
            // 5、有参数设置参数
            // 6、执行sql
            resultSet = preparedStatement.executeQuery();
            // 7、遍历结果集
            while (resultSet.next()){
                // 封装数据
                User user = new User();
                user.setId(resultSet.getInt(1));
                user.setName(resultSet.getString(2));
                user.setPass(resultSet.getString(3));
                // 把对象添加到集合中
                users.add(user);
            }
            // 返回集合
            return users;
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            // 8、关闭资源
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    resultSet.close();
                }
                if (connection != null) {
                    resultSet.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
}
